Molded insert for a molded part mold, method for producing a molded part and molded part

ABSTRACT

In order to produce molded foam parts from foam systems, such as soft, semi-hard and integral foam, foaming molds are typically used, which are produced from different base materials, depending on the intended purpose and required output or service life. Molds for producing molded foam parts are produced from steel or aluminum. A negative or undesirable property during the production of molded foam parts is that the foam adheres to the foaming molds and can often only be removed mechanically. In order to prevent this, the invention proposes a mold insert for a molded part mold, comprising a cavity, wherein the mold insert can be arranged on the molded part mold such that a volume-reduced cavity is formed in the arranged state and the mold insert contributes to creating the shape of the material.

The invention relates to a molded insert for a molded part mold, morespecifically a foam mold or galvano-mold, with an upper part and acorresponding lower part, with a cavity, more specifically a hollow,wherein the molded part mold creates a shape of a material, morespecifically a foam, that is introduced in the cavity. The inventionfurthermore relates to a method for manufacturing a molded part and to amolded part.

In order to manufacture molded foam parts from foam systems, such assoft, semi-hard, hard and integral foam, foaming molds are typicallyused, which are manufactured from different base materials, depending onthe intended use and required output or service life. Plastic material,plastic casting resins or plastic plates are used for instance forprototype or pre-series molds, whereas molds made of aluminum and/orsteel are used for production runs, respectively for production of greatquantities and complex parts.

These forms mostly consist of a lower shell and an upper shell which areconnected by lateral hinges. When closed, both “halves” form a desiredhollow space which is also called a cavity and which forms the requiredmolded part.

Slides and inserts or the like, which are inserted and actuatedmanually, semi automatically and automatically, are used for demolding“undercuts”, ribs and the like. When the form is open and/or closed, aprepared foam system is introduced into the cavity by means of a gatingsystem via a mixing head.

A negative or undesirable property of the aforementioned systems is thatthe foam adheres to the aluminum or steel of the foaming molds and canoften only be removed mechanically.

In order not to damage the parts during demolding or to be able toremove them intact, diverse release agents are used. These releaseagents prevent an “adhesion” of the foam parts to the surface of themolds. Wax-based release agents, which are liquefied by means ofsolvents in order to be applied by means of a spray pistol or a brush,are mostly used.

These release agents must be applied before each cycle. In doing so thesolvent evaporates and the wax leaves a relatively thin layer on thesurface of the mold.

This is an independent process which must be stable in order to ensurean unchanging quality of the parts. The release agents are usuallyapplied manually at the foaming plant by a worker by means of a spraypistol and the produced spray and release agent vapors must beaspirated.

Due to the repeated addition of the release layer, a thickening waxlayer forms more specifically on the smaller radiuses or on the ribs,which must be regularly removed.

The application of the release layer as well as the regular removal ofthe wax residue represents a great time and cost expenditure, associatedwith a repeated interruption of the production process.

A thin release layer also remains on the molded parts themselves. Thislayer is only unproblematic when the part does not have to be processedany further, i.e. when it is a finished part.

However, should the foam parts be subsequently laminated, this layer ofrelease agent residue makes it more difficult to glue the laminatingmaterial onto the foam. The lamination is carried out for instance bymeans of a leather or a foil. Thus, the foam part must be cleaned beforelamination.

The described release agents are also used in the manufacture of sprayskin or deep-drawn foil. So-called galvano-molds are frequently used formanufacturing spray skins and deep-drawn foils. Surfaces for doorcoverings, instrument panels or center consoles for instance aremanufactured by means of these galvano-molds.

Two-part polyurethane systems for instance are sprayed onto thesegalvano-molds. A skin is thereby formed, the thickness of which variesdepending on the incorporated quantity and which is removed from themold after a corresponding reaction time. As explained above, releaseagents, which are added either manually or automatically, must be usedin order to be able to demold or remove the produced skin.

The spray skins thus manufactured are frequently underfoamed with asupport resulting in more complex components. To this end, it is alsonecessary to ensure that the spray skin is freed of any release agents.

Another disadvantage is that galvano-molds are very expensive tomanufacture. Amongst other reasons, this is due to the fact that theseforms are frequently impressed with a surface grain, which is supposedto impress the skin to be manufactured with a leather-type surface grainfor instance.

Molded foam parts are furthermore frequently coated in so-calledcoatings. Such a coating is a protection layer. Without this protectionlayer, the surfaces of molded foam parts tend to pale and to becomebrittle when exposed to UV-light. The protection layer prevents theexposure to UV-light for instance by absorbing the UV-light.

For instance, coatings can be varnishes which are added to foam moldsbefore the foaming processes and subsequently homogeneously bond withthe foam. After demolding, the foam is then practically covered with the“coat”. The reject rate with molded foam parts covered in coating isrelatively high and can amount to up to 30%. Release agents must also beused for clean demolding.

In the manufacture of carpets, such as are used for instance in vehicleconstruction, the back side of the carpet—mostly a thermally preformedcarpet—is provided with a relatively thin-walled foam layer. The aim ofthis measure is to increase foot comfort, to absorb tolerances, and toachieve sound insulation. In order to be able to remove this extensivefoam skin from the tool after the reaction time, a thin-walled foil,which has been thermoformed beforehand, is usually placed on thecorresponding tool side as a release medium and disposed of afterstripping. This process is costly in terms of labor and costs.

The object of the invention is to improve the prior art.

The object is solved by a molded insert for a molded part mold, morespecifically a foam mold or galvano-mold, with an upper part and acorresponding lower part, with a cavity, more specifically a hollow,wherein the molded part mold creates a shape of a material, morespecifically a foam, that is introduced in the cavity, wherein themolded insert is adapted to be disposed on the molded part mold so thatin the disposed state, a cavity with a reduced volume is formed and themolded insert contributes to impressing the material.

Thus, a speedy exchange of the actual forming cavity can be ensured.

Furthermore, by removing the molded insert from the molded part mold, itis possible to wait for the reaction time to run out while alreadymanufacturing the next foam part by means of molded inserts newlyintroduced into the molded part mold.

The following terms must be explained:

The “molded part mold” is a conventionally manufactured molded partmold, for instance made of aluminum or steel, which is usually used formanufacturing a molded part. The molded part mold more specificallyincludes a “foam part” with an upper part and a corresponding lowerpart. Thereby, the upper and lower part can be separated in order toremove a molded part. Foams which reproduce the shape formed by theupper part and the lower part can furthermore be injected into theclosed foam mold, thus forming the foam molded part.

The molded part mold can furthermore be configured as a galvano-form.The galvano-form can also have an upper part and a corresponding lowerpart, only a lower part or an upper part being usually used. Thinformations such as skins can be manufactured with galvano-forms.Particularly high quality skins are produced by slightly etching thegalvano-form, so that it has a so-called grain. In this manner, skinshaving a leather-type surface structure for instance can bemanufactured.

The “molded insert” can completely fill the molded part mold or onlycover parts of the molded part mold. Finally, the molded insert can be aplate or any other substantial object which is demolded together withthe molded part.

The “cavity” is a hollow space formed by the molded part mold. In thiscontext, in a one-piece molded part mold, it is more specificallyreferred to as “hollow”. The cavity and the hollow have in common thatwhen introducing a material, such as a foam for instance, the form ofthe cavity or of the hollow is reproduced by the material.

The “introduced material” is more specifically a liquid or foamedmaterial, which forms a solid body through a hardening process. Forinstance, the material can be a plastic foam, more specifically a soft,semi-hard, hard and/or integral foam. Epoxy resins can also be used asintroduced material. Impregnated fibers such as fiber mats impregnatedwith epoxy resin (prepregs) which harden in the cavity, can also beintroduced. Powdery materials such as those used in a slush moldingmethod are also included.

In this context, “adapted to be disposed” means more specifically thatthe molded insert is adapted to the molded part mold in such a mannerthat the molded part mold receives the molded insert and that the moldedpart to be manufactured can be manufactured by means of the moldedinsert. A form-fit disposition is preferred, so that the molded partmold can act uniformly on the molded insert.

In order to manufacture molded parts without release agents, a surfaceof the molded insert related to the volume reducing cavities can have aslight or no interfacial tension. The interfacial tension must therebybe determined by the introduced material as well as the material of therelated surface. The slight interfacial tension applies morespecifically to steel and aluminum which form the surface of aconvention molded part mold.

Since the quantitative values of the interfacial tension depend on thesystem used, which interacts with the surface, it is sufficient if forthis specific system, the above condition is met. More specifically withthe “foam” system, it is important that when the foam is hardened, theinterfacial tension between the hardened foam and the surface of themolded insert be lower than with aluminum or steel.

The literature often refers to a surface tension instead of aninterfacial tension. In the following, these terms must considered assynonyms.

Since merely the material property of the surface of the molded insertis significant with regard to being free of a release agent, the surfaceof the molded insert related to the volume reducing cavity can becoated.

In another embodiment, the surface of the molded insert related to thevolume reducing cavity is formed by a plastic material. Thus,alternatives in terms of materials to aluminum and steel can be madeavailable.

Slight interfacial surface tensions or interfacial tensions can beachieved by forming the surface of the molded insert related to thevolume reducing cavity with a polyolefin, more specifically withpolyethylene.

In another embodiment, the molded insert has a temperature conductingelement which is more specifically made of metal. The temperaturegradient of the material in the molded insert relative to the actualmolded part mold made of aluminum or steel for instance, can beincreased or reduced by means of this temperature conducting element.Thus it is possible to heat the material in the molded insert as well asto efficiently cool the material in the molded insert. Metals with goodheat conducting properties are preferably used, though other heatconductors or insulators can also be used.

In order to also ensure a good temperature conductivity of the moldedinsert, the thickness of the material of the molded insert can amount tobetween 0.8 mm and 8 mm and most preferably approximately 2.5 mm. It isthereby particularly advantageous for heat conductivity to use very lowmaterial thicknesses.

In another embodiment the molded insert is manufactured as an injectionmolded part. In this manner, molded insert can be manufacture in greatnumbers, thus considerably reducing costs.

In order to ensure a determined fixation and a determined detach of themolded insert into or from the molded part mold, the molded insert canhave a fastening element which allows a detachable solid assembly in themolded part mold. More specifically clamping or screwing devices arepossible embodiments of the fastening element.

In order to give stability to the molded insert, the molded insert canform a support structure.

In order to reduce weight or to obtain a determined heat insulation, thesupport structure can have hollow spaces.

In another embodiment, joined partial molded inserts form the moldedinsert. More specifically extensive molded inserts such as carpetcoverings in automobiles can thus be manufactured.

In order to form a molded insert with the partial molded inserts that isas homogeneous as possible, the partial molded inserts can haveconnection elements which can form a stable molded insert. Thereby, theconnection elements can for instance be base on a type of groove andspring principle. Screw connections with dedicated threads can also beimplemented.

In another aspect of the invention, the object can be solved by a methodfor manufacturing a molded part with a molded part mold with a cavitywhich impresses a form onto an introduced material.

1. A mold insert for a metallic molded part mold, more specifically fora foam or galvano-mold, with an upper part and a matching lower part,with a cavity, more specifically a hollow, the molded part moldimpressing a shape onto a material, more specifically a foam introducedinto the cavity, wherein the mold insert is an injection-molded partwhich is adapted to be disposed without a release agent onto the surfaceof the molded part mold, the material thickness of the mold insertamounting to between 0.8 mm and 8 mm, so that in the disposed state acorrespondingly volume-reduced cavity is formed and the mold insertcontributes to impressing a shape onto the material inside thevolume-reduced cavity, more specifically on its entire surface.
 2. Themold insert according to claim 1, wherein a surface of the mold insertmatching the volume-reduced cavity has a slight or no interfacialtension.
 3. The mold insert according to claim 1, wherein the surface ofthe mold insert matching the volume-reduced cavity is coated.
 4. Themold insert according to claim 1, wherein the surface of the mold insertmatching the volume-reduced cavity is formed by a plastic material. 5.The mold insert according to claim 1, wherein the surface of the moldinsert matching the volume-reduced cavity is formed by a polyolefin,more specifically a polyethylene.
 6. The mold insert according to claim1, further comprising a temperature conducting element.
 7. The moldinsert according to claim 1, wherein the material thickness of the moldinsert amounts to approximately 2.5 mm.
 8. The mold insert according toclaim 1, further comprising a fastening element, which allows adetachable firm connection with the molded part mold.
 9. The mold insertaccording to claim 1, further comprising a support structure.
 10. Themold insert according to claim 9, wherein the support structure hashollow spaces.
 11. The mold insert according to claim 1, wherein it isformed by assembled partial mold inserts.
 12. The mold insert accordingto claim 11, wherein the partial mold inserts have connection elements.13. A device for manufacturing a molded part with a molded part moldwith a cavity which impresses a shape onto an introduced material,wherein a mold insert for a metallic molded part mold, more specificallyfor a foam or galvano-mold, with an upper part and a matching lowerpart, with a cavity, more specifically a hollow, the molded part moldimpressing a shape onto a material, more specifically a foam introducedinto the cavity, wherein the mold insert is an injection-molded partwhich is adapted to be disposed without a release agent onto the surfaceof the molded part mold, the material thickness of the mold insertamounting to between 0.8 mm and 8 mm, so that in the disposed state acorrespondingly volume-reduced cavity is formed and the mold insertcontributes to impressing a shape onto the material inside thevolume-reduced cavity, more specifically on its entire surface, saidmold insert is adapted to be disposed without release agent in themolded part mold, whereby a volume-reduced cavity is formed whichimpresses a shape onto a material introduced into the volume-reducedcavity, which has a reduced volume as compared to when a material isintroduced into the cavity without a molded part.
 14. The deviceaccording to claim 13, wherein the volume-reduced cavity forms a shapeof the molded part to be manufactured, the size of the cavity formed bythe molded part mold being increased by the thickness of the material ofthe mold insert.
 15. The device according to claim 13, wherein themolded part mold has a matching receptacle for the fastening element.16. The device according to claim 13, wherein the molded part mold ismade of a metal, more specifically stainless steel, steel, aluminum,and/or magnesium, or an alloy.
 17. The device according to claim 13,wherein the molded part mold has an upper part and a lower part.
 18. Amethod for manufacturing a molded foam part, the method including thefollowing steps: introducing a mold insert for a metallic molded partmold, more specifically for a foam or galvano-mold, with an upper partand a matching lower part, with a cavity, more specifically a hollow,the molded part mold impressing a shape onto a material, morespecifically a foam introduced into the cavity, wherein the mold insertis an injection-molded part which is adapted to be disposed without arelease agent onto the surface of the molded part mold, the materialthickness of the mold insert amounting to between 0.8 mm and 8 mm, sothat in the disposed state a correspondingly volume-reduced cavity isformed and the mold insert contributes to impressing a shape onto thematerial inside the volume-reduced cavity, more specifically on itsentire surface without a release agent into the molded part mold of adevice for manufacturing a molded part with a molded part mold with acavity which impresses a shape onto an introduced material, wherein saidmold insert is adapted to be disposed without release agent in themolded part mold, whereby a volume-reduced cavity is formed whichimpresses a shape onto a material introduced into the volume-reducedcavity, which has a reduced volume as compared to when a material isintroduced into the cavity without a molded part, injecting a moldablematerial, more specifically a foam into the volume-reduced cavity, sothat the volume-reduced cavity impresses the shape of the molded partonto the material in such a manner that a molded part is formed,demolding the molded part, and removing the mold insert from the moldedpart mold.
 19. The method according to claim 18, wherein other moldedparts are manufactured before removing the mold insert.
 20. The methodaccording to claim 18, further comprising a coating layer, which isimpressed onto the molded part during manufacture, is applied to themold insert before injecting the moldable material.
 21. The methodaccording to claim 18, further comprising introducing a molded partsupport before injecting the moldable material into the cavity or thevolume-reduced cavity.
 22. The method according to claim 18, furthercomprising replacing said molded insert with another mold insert afterremoving the molded insert from said molded part mold.
 23. The methodaccording to claim 18, wherein said another mold insert is a previouslyused molded insert which has been cleaned and reused.
 24. A molded foampart which is manufactured with a device for manufacturing a molded partwith a molded part mold with a cavity which impresses a shape onto anintroduced material, wherein a mold insert for a metallic molded partmold, more specifically for a foam or galvano-mold, with an upper partand a matching lower part, with a cavity, more specifically a hollow,the molded part mold impressing a shape onto a material, morespecifically a foam introduced into the cavity, wherein the mold insertis an injection-molded part which is adapted to be disposed without arelease agent onto the surface of the molded part mold, the materialthickness of the mold insert amounting to between 0.8 mm and 8 mm, sothat in the disposed state a correspondingly volume-reduced cavity isformed and the mold insert contributes to impressing a shape onto thematerial inside the volume-reduced cavity, more specifically on itsentire surface, said mold insert is adapted to be disposed withoutrelease agent in the molded part mold, whereby a volume-reduced cavityis formed which impresses a shape onto a material introduced into thevolume-reduced cavity, which has a reduced volume as compared to when amaterial is introduced into the cavity without a molded part; and/oraccording to a method for manufacturing a molded foam part, the methodincluding the following steps: introducing a mold insert for a metallicmolded part mold, more specifically for a foam or galvano-mold, with anupper part and a matching lower part, with a cavity, molded part moldimpressing a shape onto a material, more specifically a foam introducedinto the cavity, wherein the mold insert is an injection-molded partwhich is adapted to be disposed without a release agent onto the surfaceof the molded part mold, the material thickness of the mold insertamounting to between 0.8 mm and 8 mm, so that in the disposed state acorrespondingly volume-reduced cavity is formed and the mold insertcontributes to impressing a shape onto the material inside thevolume-reduced cavity, more specifically on its entire surface without arelease agent into the molded part mold of a device for manufacturing amolded part with a molded part mold with a cavity which impresses ashape onto an introduced material, wherein said mold insert is adaptedto be disposed without release agent in the molded part mold, whereby avolume-reduced cavity is formed which impresses a shape onto a materialintroduced into the volume-reduced cavity, which has a reduced volume ascompared to when a material is introduced into the cavity without amolded part, injecting a moldable material, more specifically a foaminto the volume-reduced cavity, so that the volume-reduced cavityimpresses the shape of the molded part onto the material in such amanner that a molded part is formed, demolding the molded part, andremoving the mold insert from the molded part mold.